The Collaborative International Dictionary of English v.0.48:

Sea eagle \Sea" ea"gle\
   1. (Zool.) Any one of several species of fish-eating eagles
      of the genus Haliaeetus and allied genera, as the North
      Pacific sea eagle (Haliaeetus pelagicus), which has
      white shoulders, head, rump, and tail; the European
      white-tailed eagle (Haliaeetus albicilla); and the
      Indian white-tailed sea eagle, or fishing eagle
      (Polioaetus ichthyaetus). The bald eagle and the osprey
      are also sometimes classed as sea eagles.
      [1913 Webster]

   2. (Zool.) The eagle ray. See under Ray.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sea eagle
    n 1: large harmless hawk found worldwide that feeds on fish and
         builds a bulky nest often occupied for years [syn:
         osprey, fish hawk, fish eagle, sea eagle, Pandion
         haliaetus]
    2: any of various large eagles that usually feed on fish